Monday, 15 August 2011

Indiana State Fair Stage Roof Collapse

Well, it's happened again. A second major stage roof collapse in North America in less than a month, this time at the Indiana State Fair, and this time resulting in five deaths and over forty-five injuries.

What I keep reading in "statements" from the stage roof suppliers in all these and other cases is that they claim the collapses were caused by sudden gusts of wind that exceeded design limits. What also seems to be common is that at these locations, many other tents in the general vicinity have remained standing and unharmed. So what is going on? There are a couple of possibilities:

1. The design of the stage roof does not meet the standards of ANSI E1.21 - 2006 regarding wind loading as well as other support requirements.
2. The wind really was higher than expected and also there was insufficient time to remove roof components to prevent damage.

At least initially, my thought is to ignore possibility #2 and focus on the design of the structure.

Now I come from an engineering background so this stuff is pretty important. While in the Air Force, I was assigned to investigate two aircraft crashes in the course of my career. The first thing that happened when an aircraft went down was that all the flight and engineering logs of that aircraft were immediately impounded pending a formal investigation. I recommend that our industry (special events) initiate the same requirement for any incidents such as stage roof collapses that result in injury or death. This would require that the event manager impound and demand copies of, all applicable subcontractor documentation for any contractors directly involved with the construction or erection of this type of structure, ideally within no more than two hours of the incident (leaves little time to "cook the books"). This documentation would include such paperwork as contracts with other subcontractors, engineering drawings and calculations supporting the design of the structure and the wind load ratings, proof of compliance with material design standards (e.g. trussing, roof fabric), and proof of compliance with personnel safety regulations.

There is another issue involved here and that is the difference between what is required by law and what is voluntary. Usually, within a province or state, personnel safety regulations are enforceable by law, whereas standards are only voluntary. That subtle difference may make a gigantic difference in these latest cases when it comes to litigation and placing blame as well as claiming damages.

My soapbox  - and this is a continuing theme in my books - is that compliance with standards should be written into all contracts so that everyone from the event manager down is covered as much as possible with respect to disasters. This is what proper risk management is all about, and it makes the compliance legally enforceable under the terms of the contract.

It will be interesting to see what the investigations dig up in all these recent cases

Monday, 1 August 2011

Crazy Summer Weather and Stage Roof Collapses

Every recent summer seems to bring out not only the worst in weather but also dangerous situations at summer festivals that accompany the weather.

Exactly two years ago today, a main stage roof at the Big Valley Jamboree in Camrose, Alberta collapsed, killing one person and injuring 75 as a result of a sudden storm and high winds. As of last Friday, 33 charges were laid stemming from that collapse.

On July 17th this year, a main stage collapsed at the Ottawa Bluesfest while Cheap Trick was playing. This collapse injured at least 5 people, one seriously. The collapse was also attributable to a violent gust of wind.

Although I cannot make a comment about how the producers of either event handled the respective situations, from what I can glean from news reports, they were both aware of the ANSI standard that governs the construction and safety of outdoor stage roof structures, particularly with respect to wind gusts. For reference, see American National Standard E1.21 - 2006 - Entertainment Technology, Temporary Ground-Supported Overhead Structures Used to Cover the Stage Areas and Support Equipment in the Production of Outdoor Entertainment Events. It is available at

What most worries me as I read these reports is not whether the producers of these large festivals followed the standards, it is how many producers and planners of much smaller community and private outdoor summer events even know that such a standard exists, and what kind of liability situations they are unknowingly placing themselves and other organizations in. These are strict guidelines that call for - among other things - full documentation of engineering analysis and a complete Operations Management Plan that covers situations with high winds. Below are two applicable sections of the standard:

3.5.2 Wind loading The wind load on all exposed surfaces including but not limited to truss and tower sections, scaffolding, roof skin, back drops, banners, advertisements, and suspended equipment shall be considered. The overall stability and resistance to wind uplift and overturning forces shall be provided by means such as wire guys anchored to ground anchors (or ballast), diagonal braces, ballast applied to the tower sections, self weight of roof top (the dead load) and live loads. The design wind speed for structures as defined by this document shall be 0.75 times the basic wind speed defined in ASCE 7. Where a structure will be erected in an area prone to hurricanes, and precautionary measures can be taken such as dismantling and adequate securing in the event of a hurricane warning, a basic wind speed of 90mph, 3 second gust, shall be allowed per ASCE 37, section 6.2.1. A reduction in effective wind area can be permitted, provided that such elements can be removed in less than 5 minutes. The method of wind monitoring and removal of the equipment shall be clearly defined in the Operations Management Plan. Not withstanding the above, the structure shall be designed to resist wind forces on all elements associated with the design wind speed of 40mph.

3.5.3 Operations Management Plan The Operations Management Plan shall be prepared by the User and his engineering advisors. Reference shall be made to Clause 5.2.3 of this document. The Operations Management Plan shall be based on sound engineering analysis and the allowable loads as defined in the engineering documentation. The Operations Management Plan shall define the actions to be taken for different parts of the structure and cladding (where applicable) under prescribed loading conditions, with particular regard to wind loads. No action shall be taken that shall reduce the overall lateral stability of the structure.

The standard goes on to discuss the need for proper consideration of the supporting ground surface, lateral loading, proper design of trussing and the provision of associated drawings and calculations, plus a host of other detailed requirements.

I've hammered away at this topic before in this blog and also in my books. My contention is that full compliance with this ANSI standard not only should, but must, be written into every contract that an event planner/manager or producer has with a supplier who has anything to do with the construction and/or erection of a stage roof system to be used outdoors. It does not matter how big or small your event may be. You can be sure, that come the day of reckoning when a disaster happens like those mentioned above, the courts are going to be calling for a detailed paper trail.

Beware of summer storms!